We come now to what is recognized as Plato’s magnum opus, the Republic. A long dialogue in ten books (originally, ten papyrus rolls), it is a comprehensive study of Plato’s system of thought. It is likely to have been written over an extended period of time and perhaps presented in shorter versions from time to time. But when it was completed, it offered the most thorough statement of Plato’s thought in a dramatic setting, engaging a series of (sometimes loosely) related topics that together presented a systematic view of Plato’s thought, now clearly distinct from Socrates’ philosophy—though with Socrates as the narrator and spokesman.
We meet Socrates at a new festival honoring the Thracian goddess Bendis in the port of Piraeus. As he is about to return home, Polemarchus hails him and invites him to his house, where his aged father Cephalus presides, with the promise of an overnight torch race. The occasion will turn into an all-night discussion of philosophy with Socrates as the master of ceremonies.
Socrates converses with Cephalus, who is concerned not to leave this life without being reconciled with gods and men for wrongs he may have done them. Socrates seizes on a remark of the patriarch to extract a definition of justice: justice is paying one’s debts, returning what is owed. Cephalus, the model of piety, excuses himself do offer sacrifices to the gods—to pay his debts—while his son Polemarchus approves the proffered definition and takes up the discussion with Socrates. Socrates brings up the example of a man demanding his weapons back so that he can attack someone he is angry with. Today, with terrible instances of gun violence, the example seems especially chilling. Surely it is not just to return weapons to someone in a murderous rage.
In an attempt to improve on the first definition, Polemarchus suggests that justice consists of doing good to friends and harm to enemies.[1] This echoes a common attitude of popular morality.[2] Suppose, Socrates objects, you have friends who are bad and enemies who are good; then it will be just to do good the bad people and do harm to good people. With Socrates’ help, Polemarchus modifies the definition to say that justice consists of doing good to friends who are good and harm to enemies who are bad. [3]
Now, however, Socrates points out that to harm someone is to make that person worse. To make someone morally worse would be to make someone more unjust. How can it be the work of justice to make people more unjust?
At this point another guest at the party, Thrasymachus the sophist, breaks in and loudly accuses Socrates of refuting every definition others offer while providing no positive guidance himself. Thraysmachus obviously regards himself as an expert on the subject. The audience begs him to give his own definition of justice to enlighten them. “Listen, then,” he says. “I declare that justice is nothing but the advantage of the stronger.” Silence. “Why don’t you applaud? — Because you just won’t!”[4]
Socrates says he merely wants to understand what Thrasymachus is saying. The sophist replies that whatever party is in power, democracy or tyranny, for instance, makes laws for its own advantage. Socrates asks if the rulers are always infallible, or whether they can make mistakes. They can make mistakes. Then they may pass laws that are not to their own advantage. When they do that, the rulers are commanding people to act in a way contrary to the rulers’ advantage, and anything the citizens do will be both just and unjust.
Thraysmachus now changes his tack. If a ruler makes an error, he is not the stronger. He makes an analogy to the crafts. When a doctor makes an error, he is no longer acting as a doctor. Consequently, “According to the exact account, which you insist on, no craftsman ever makes a mistake.”[5]
Thrasymachus has blundered into an area where Socrates has the advantage. The historic Socrates seems to have delighted in the Craft Analogy, likening virtue to the work of a craft, a technē.[6] Yes, the doctor as a craftsman or an expert in applied science uses knowledge to make someone better. But the person he helps, the patient, is not the stronger, but the weaker person, at least in respect of health. A craft harnesses knowledge of the stronger (the healer) to benefit the weaker (the patient). Similarly, the shipmaster benefits the sailors and the passengers on the ship with his expertise in navigation and ship handling.
Thrasymachus replies that the shepherd does not seek to benefit the sheep but to make a living by his trade. Socrates replies that we must distinguish between the art of animal husbandry and the art of money-making. Insofar as the shepherd is a shepherd, he cares for the sheep; insofar as he is making money, he gets advantage from the craft. Similarly, the doctor charges money, precisely because the art of medicine per se is not to the doctor’s advantage, but to the patient’s.
Thrasymachus now changes course. He argues now that injustice is a virtue and justice is naivete. The unjust person takes advantage of the just, and lives the better life. This move requires Socrates to develop a different strategy to counter his argument. But Socrates does so, by pointing out that if the just person—think again of the craftsman—does something right, for instance, adds two and two to get four, the unjust person must try to outdo that person, and must come up with a different sum—which will be wrong and somehow self-defeating. It turns out, Socrates concludes, the justice is wisdom, and injustice is ignorance.[7]
A further objection is that the perfectly unjust person can never cooperate with others to accomplish anything. To rob a bank, for instance, a robber would have to agree with other robbers—who, as robbers, will be committed to injustice. One robber should ideally drive the getaway car, one would carry the money, one would hold a gun, and one would be a lookout. But if they were completely unjust, the lookout would not look out for the other robbers, the gunman would not bring a gun, the bagman would not bring a bag, and the driver would not be waiting for the other robbers after the heist. In other words, injustice would be self-defeating. Robbers would need a modicum of justice merely to pull off a heist. But then they would have to trust their fellow robbers to share the spoils equally; yet they would know in advance that no one in the group was trustworthy. (Think of movies about robberies in which the robbers double-cross each other in the end.)
Finally, Socrates offers a positive argument, the argument from function. Does a horse have a function—something that it does best? Yes. And similarly a tool and an organ like an eye have functions. Does each of these things have a virtue, an ability to perform well its function? Yes. Does a soul also have a function? Yes. Its function is to live, rule, and deliberate? Yes. Is there then a virtue of soul? Yes. Is justice the virtue of soul? Yes. Then to live well and be happy would be the result of a soul’s being just.
At the end, the combative Thrasymachus is reduced to sullen silence. Socrates has vindicated justice. But only partially. For, according to Socrates, we cannot determine anything for certain about justice without properly defining it. And we have not yet defined justice. This becomes the challenge for the remaining books of the Republic: define justice and show how to realize it fully.
[1] Plato Republic I, 332d.
[2] Lysias 9.20; Euripides Medea 807-10; see Dover 1974: 181-184 for numerous citations of similar attitudes.
[3] Plato Republic I, 335a.
[4].Plato Republic I,338c.
[5] Plato Republic I, 340e.
[6] See Irwin 1977: 71-77; Kube 1969.
[7] Plato Republic I, 351a.